Submarines operate in the 1000s of PPM CO2 range and the sailors aboard generally do not experience any ill effects. This was tested and no deficits were found even at 15,000 PPM: https://asma.kglmeridian.com/view/journals/amhp/89/6/article...

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amluto 28 minutes ago | parent | next [-]

A major confounding factor is everything else in the air. Humans produce lots of different gases, and CO2 is usually a proxy for the overall concentration of our effluent gases. But in a submarine, or in some buildings, there are gas filters (usually carbon, possibly with various modifications) that can remove or destroy some of these gases but have no effect on CO2. So the air in a submarine at 15000ppm CO2 could be very different from the air in a an unventilated room that reaches 15000ppm CO2.

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w-m 7 hours ago | parent | prev | next [-]

I don't think you can cleanly compare this: In the study, they added CO2 to the room, while keeping O2 at normoxic levels throughout the experiment. In your meeting room, O2 levels will be dropping in lock-step with the CO2-levels rising. It may be the lack of oxygen that leads to drowsiness, not the additional CO2. But it's the CO2 levels that you can measure as a good proxy of overall air quality.

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KerrickStaley 7 hours ago | parent | next [-]

I don't think this is correct. The concentration of CO2 in air is about 0.04%, whereas the concentration of oxygen is 20%, so the partial pressure of oxygen is about 500x higher. This means that if, for example, 10% of the oxygen in a room spontaneously disappeared, it would be replaced about sqrt(500) = 22x faster through leaks in the room than a 10% spontaneous CO2 increase would dissipate. (This ignores a small effect due to the different density of the two gases).

So in practice the oxygen level can never drift meaningfully far from the atmospheric pressure, whereas carbon dioxide easily can because the pressures involved are so low.

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w-m 6 hours ago | parent [-]

Ok, fair points, including the sister comment, it's likely not a drop in O2 levels.

But then why can we see problems with concentration in studies of people in poorly ventilated rooms, but not replicate that when just adding CO2 to normal air? What is the CO2 that we can measure in meeting rooms actually a proxy for?

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tux3 6 hours ago | parent | next [-]

The Satish 2012 study that seems to have started this trend was a small cohort of 22 people split in 6 smaller groups where they also just injected pure CO2 in a small room. There have been several attempts to reproduce, which sometimes found no clear effect, or a significantly smaller effect.

This original study has been used to market these CO2 monitors for years, but the evidence is quite thin and doesn't support a strong effect. It seems likely that there is a small effect, and it has been wildly exaggerated thanks to a small study with N=22.

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fooblaster 2 hours ago | parent [-]

So is this all bullshit?

	▲	thomasmg an hour ago \| parent [-]
		Lacking a large study, we can't know. Of course the CO2 meter companies benefit if people believe it is true.

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halper 5 hours ago | parent | prev [-]

Can it not just be that what happens in stuffy meeting rooms is boring? Opening the windows changes the temperature, the noise levels, perhaps the light levels ≈ adds some novelty, which makes you feel a bit more awake.

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hahahaa 7 hours ago | parent | prev [-]

O2 is 200000ppm so if co2 goes up 400 to 2000ppm does o2 go down to 198400ppm?

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Robin_Message 7 hours ago | parent | prev | next [-]

If that study was of submariners, is it possible long-term high-level exposure causes the body to adapt?

I am suspicious of 0.1% having a significant effect though, given oxygen is around 20% and we naturally exhale a couple of percent CO2.

	▲	pishpash 6 hours ago \| parent [-]
		I mean that can't be right, as the body's breathing response is triggered by that amount of CO2 buildup. It's not about what's in the air. It's about what the body can take up. Maybe submariners are self-selected to be more physically fit, e.g. larger heart, lung capacity etc. to compensate.

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brookst 7 hours ago | parent | prev | next [-]

Though that study included a 45 minute acclimation period. Appropriate for submarines, but I wonder what the results would be in the first 1 / 5 / 10 minutes.

	▲	threatripper 7 hours ago \| parent [-]
		CO2 levels will rise much more slowly to such high levels even in a small room.

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mppm 2 hours ago | parent | prev | next [-]

... which is entirely unsurprising given that exhaled air is about 50.000 ppm CO2 and can vary by several 10.000s depending on depth and rate of breathing. I actually consider the recent wave of findings that CO2 levels as low as 500-1000 ppm measurably affect cognitive performance and well-being to be a great example of how you can prove literally anything with statistics and a sufficiently small sample size.

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dev1ycan 2 hours ago | parent | prev | next [-]

Submarineers also are hand picked due to their great lung capacity...

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nok22kon 5 hours ago | parent | prev | next [-]

could be a selection effect at work

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culturestate 7 hours ago | parent | prev [-]

One key difference is that submariners are rigorously trained to operate effectively in less-than-ideal environmental conditions, whereas Bob from accounting probably is not.